Update CI

[agateau-gg]

Following warnings reported during the release, this PR updates the CI:

• actions/cache: v3 → v4
• codecov: v3 → v4
• actions/create-release: replace with use of gh release command (the action is unmaintained). The way gh release is used here is similar to what the ggshield tag workflow does.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.55%. Comparing base (215f529) to head (136ef69).
Report is 32 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #130      +/-   ##
==========================================
+ Coverage   94.45%   94.55%   +0.09%     
==========================================
  Files           6        6              
  Lines         830      918      +88     
==========================================
+ Hits          784      868      +84     
- Misses         46       50       +4     

Flag	Coverage Δ
unittests	94.55% <ø> (+0.09%)	⬆️

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